This is something I’ve wondered for some time now. Hemorrhoids and colitis (an inflamation of the large colon) both involve, or would seem to involve, feces coming into direct contact with open, bleeding tissue. Yet in spite of all the trouble these conditions do cause, they generally don’t seem to lead to infection, even though feces in contact with, say, a wound on your hand surely would. Why is this? And if the body has a way of avoiding infection like this, why doesn’t it use it everywhere on your body?
Excellent question - I wondered also. I guessed for hemorrhoids that the blood was at higher pressure and the sufferer tends to bleed pretty profusely for such a small wound, so washing infection out. This wouldn’t work for some other problems because big wounds would lose too much blood and tiny wounds like splinters aren’t mechanically open enough to bleed much. No idea about colitis, though.
IANAD, but I do have Crohn’s disease. I would say that when I have active inflamation going on, I also hve lots of diarrhea and am not eating much, if at all. So there’s potentially not a lot in the digestive system after a day or two. This is just IME, a WAG, and others MMV.
It is a testamonial to the immune system. It can deal with alot that is thrown at it , will develop immunites from what it already encountered, but does struggle to respond to some new or very old invaders.
Chalk it up to evolution, I suppose. Individuals who tend to get infections from their own digestive and excretory systems tend to not live long enough to reproduce.
Which doesn’t answer the deeper question as to how the body really recognizes ‘self’ from ‘non-self’ infectious agents. I know lots of theories abounded years ago when I was in training, but I’m not really sure about current thoughts on the subject.
Don’t they get infected? I have had several bouts of diverticulitus (infection of the diverticulii); isn’t this similar to colitis? It sure felt like an infection (fever, elevated white cell count, swelling) and each time I was required to take enough antibiotics and anti-infectives (are these the same?) to choke a horse.
Anyway, the evolution thing sounds right. I came to the realization in my second bout that if it had been fifty years earlier I would probably be dead. It is a very nasty and persistant infection.
Diverticulitus and diverticulosis run in my family. Every male in my family (on my dad’s side) has had a bowell resection before they were 45. I’ll probably have to have one before I am forty even though I have always had a healthy, high-fiber diet.
Certainly diverticulae get infected. But they are structural anomalies of the colon, pouches which get packed with bacteria, can’t empty, and often strangulate and cause tissue to die. In some ways, the appendix is like a larger diverticulum.
And colitis is inflammation in the bowel wall, on which bacteria rub every minute of every day. Many portals of entry for bacteria into the system when the colon wall is inflamed.
But the amazing thing isn’t that they get infected, it’s that they don’t do it far far more often!
Nor do fissures in the anal mucosa get infected often. Imagine them as being analogous to chapped, cracked lips, except on the exit end, where they’re bathed in coliform bacterial constantly. Yet they heal up just fine in the vast majority of cases.
Again, the macro answer to why we’re not constantly sickening and dying from these things is natural selection. If one’s immune system didn’t resist infection from everyday inoculation with potentially deadly bacteria, one wouldn’t survive to adolescence.
Maybe KarlGauss will enlighten us. He’s better versed in immunology than I am. Hell, so’s DoctorJ these days, I’d wager! He’s getting the latest edumacation in medicine almost daily! I’m just working on not being too out of date.
I’m not sure if this is part of the answer, but it seems like a possibility:
I’ve recently heard several talks by a woman who is studying the bacteria which normally live in the gut. She’s found that the normal flora of the gut produce a signal which dampens the immune response. These unknown (to my knowledge) signals act only locally, so at the surface of the gut, immune function is diminished. However, the systemic immune system remains unaffected. It is very interesting work and still in the very early stages.
On the flip-side, competition from other bacterial species keeps the community in check.
With these two things together, I could see how the gut is not a great site of pathologic infection. Bacteria will readily grow, but not out of control. Also, many, if not most, of the symptoms of infection are a result of the immune response. With the immune system dampened, it would probably take a raging infection for symptoms to reach a clinical level.
Which question specifically would you like answered? And are we talking Ulcerative Colitis, or Crohns Disease? The answer could be different depending on which colitis.
Ulcerative colitis is what I’ve got, and seemingly a rather mild case. Still, there’s bleeding often enough that I’m curious about this whole (lack of) infection deal. Am I just generally immune to the nasty critters in my colon? Or is there something specific about the colon that prevents the infections?
There are a number of reasons that we are not constantly overwhelmed by infections from the colon - or the mouth or gyn tracts either, for that matter.
Mucous membranes like those lining the GI, respiratory, and genitourinary tracts are associated with a lot of lymphoid tissue like the tonsils, MALT cells, Peyer’s patches, and mesenteric lymph nodes. This lymphoid tissue works constantly to filter out bacteria that may get in through breaks in the mucosa. The lymphatic drainage of the gut is much greater than that of, say, subcutaneous fat of the abdomen. The mucous membrane of the gut also has special forms of antibodies bound to its surface (as opposed to circulating in the bloodstream) to ‘preemptively’ bind foreign antigens.
Mucous membranes also tend to have a rich blood supply, which provides access for large amounts of white blood cells, antibodies, etc. A rich blood supply improves your chances of fighting off localized infection, which is why your body reacts to infection with inflammation. This localized dilation of blood vessels causes the redness and swelling around a healing wound.
Most injuries to the GI tract represent superficial tears of the mucosa rather than deep penetrating wounds. These superficial wounds heal more easily than deep wounds - there is nowhere for infected material to collect, forming an abscess that provides a safe haven for bacteria while limiting access by white blood cells. A person with diverticulosis has tiny outpouchings of the colon wall that remain asymptomatic until they become blocked at the opening, at which point bacteria breed freely in the enclosed space, leading to infection and diverticlulitis.
Millions of years of evolution have resulted in a fantastically complex interaction between our immune system and the many species of normal GI flora. Many pathogens are outcompeted by relatively benign species that flourish in the gut but are not good at invading healthy tissue. Diarrhea can help flush pathogens from the gut but can be ‘exploited’ by some bugs to spread large numbers of themselves and infect others (eg cholera). Salivary and gastric enzymes, stomach acid, bile, and pancreatic secretions all destroy many pathogens on contact.
[is this a hijack?]
So let me ask you brossa, Qadgop, DoctorJ or anyone else who feels like weighing in a question about diverticulitus. Obviously I have diverticulosis since I have had several bouts of diveritculitus. What can I do to keep it in the “osis” stage? I already have a very high fiber diet (30-40 grams /day) and I have never had a low fiber diet. I get tons of fluids, manage my stress, exercise, and am otherwise reasonable healthy for my 35 years of age. But I have still had 1 bout/year for the last 3 years. Typically I do either 1 or 2 rounds of Flagyl and Cipro (which just about kills me) and then do everything I can to keep it at bay. My doc (a GP) says to keep doing what I am doing and does not really give me any more info. I know I need to see a GI, but I am worried that they will just want to cut (this is what my fathers and my uncles say, that they went to a GI and the GI said “lets schedule surgery” without even doing an exam). I would rather not have a resection if there is any way to avoid it.
Even though it seems like I am asking for advice, I’m not. Only my doctor can examine me so any advice I get here can only go so far. I take this very seroiusly and know the risks and the necessity of having competent (onsite) medical help for this. Regardless, I would like to be educated on this by people that know more than I do and communicate more than my doctor does.
[/potential hijack]
A few good links on Diverticulosis and Diverticulitis. The first two are for the layperson, the last for medical professionals, but it’s still a good overview, and not hard to read.
Generally, most cases of diverticulitis can be managed medically. But about 20-30% of patients with diverticulitis will eventually need surgery. The way to avoid the surgery is to avoid diverticulitis; Managing one’s diverticulosis thru High fiber diet! Some experts think a low fat diet can also help reduce the risk, but that is controversial.
Also, see one’s doc at the first onset of symtoms of diverticulitis: Abrupt pain on the left lower abdomen. Other symptoms can include fever, loss of appetite, nausea, or vomiting.
Interestingly, the old advice about avoiding seeds and nuts appears to be Wrong!
